The present invention is concerned with a storage apparatus in which a plurality of individual items are stored and can be selectively accessed as required. In particular, the present invention is concerned with a storage apparatus in which chemical or biological samples are stored in a temperature controlled, sealed environment, and can be selectively deposited in, and removed from, the storage apparatus.
By “temperature controlled environment” we mean both environments below ambient (e.g. low temperature storage) and above ambient (e.g. incubators).
It is known to provide storage for chemical or biological samples. Such storage facilities are designed to store chemical or biological samples for long periods of time. In order to avoid degradation, such samples are stored at very low temperatures-typically in the order of minus 20 degrees down to minus 80 degrees Celsius and even lower. It is desirable to minimise the amount of space such storage facilities use, because laboratory space is often at a premium. Also, refrigeration to such temperatures uses energy, and because it is desirable to store many such samples, they are usually stored in a high density arrangement to minimise volume, and therefore maximise energy efficiency. The downside of high density storage is that it makes access to a single sample problematic, particularly if it lies in the centre of the storage arrangement. Access to a single sample requires movement of the surrounding samples, which may necessitate bringing them into a higher temperature environment, which is undesirable.
Some known devices utilise a Cartesian (XYZ) robot system to select individual items from a high density array. In such systems the robot is positioned within a cold zone. Typically such a zone will be at minus 20 degrees Celsius. Groups of samples can be extracted from the storage chamber (at, say, minus 80 degrees Celsius) via a simple mechanism individual items can then be selected and moved to ambient for examination. It is difficult to access an individual sample without exposing the surrounding samples to higher temperatures (either minus 20 degrees or ambient). Disadvantageously, placing the robot in a cold zone means that not only does the robot have to function in such an environment, it becomes difficult to service. It also means that the cold storage container has to be large, which is inefficient as energy must be expended keeping the robot at a low temperature, as well as the samples.
What is required is a storage apparatus which can pick an individual item from a high density container whilst minimising the exposure time of the surrounding items to higher temperatures. What is also required is a picking arrangement which takes up minimal space so it can be placed in the cold zone.
It will be noted that these requirements are apparent in any system where a plurality of items are stored at high density in a controlled environment, when exposure to ambient conditions may be hazardous to the integrity of the item. For example, this may be “clean” storage, storage in an inert gas, or “hot” storage such as an incubator instead of cold storage.
It is an aim of the present invention to provide a storage apparatus which can externally pick individual items from high density storage whilst minimising the exposure of the surrounding items to high temperatures, thus overcoming, or at least mitigating, the disadvantages of the prior art.
According to a first aspect of the present invention there is provided a storage apparatus comprising an array of item storage formations, a first member rotatable with respect to the array about a first axis, a selector mounted on the first member, the selector being rotatable with respect to the first member about a second axis, parallel to and offset from the first axis, the selector comprising an item transfer conduit offset from the second axis, in which the first member and the second member are configured for rotation about the first and second axes respectively to selectively align the item transfer conduit with one of the array of item storage formations to extract the item from the array.
By “transfer conduit” we mean a passage, conduit, bore or orifice through which items can pass.
Advantageously, the provision of such a system using an epicyclic selector provides fast access to an annular array of item storage formations. The fact that the first member and the selector are rotatable to position the transfer conduit makes them easier to seal against a tank wall. The epicyclic mechanism is also very compact compared to traditional Cartesian systems, which require a lot of space, and in particular extend outside the workspace (for mounting and actuating the rails or racks).
Preferably a temporary storage unit, or “catcher”, is mounted proximate the selector, the temporary storage unit defining a plurality of chambers for temporary storage of items. The temporary storage unit is preferably in communication with the transfer conduit on the opposite side of the selector to the tank, and is movably mounted relative to the selector to place the transfer conduit in communication with an individual one of the plurality of chambers. Advantageously, should the items stored in the volume be vertically stacked (i.e. parallel to the axes), the items on top of an item of interest can be extracted and stored in the temporary storage unit before the item of interest is extracted. The temporarily stored items can then be returned to the array.
Preferably the temporary storage unit is mounted for concentric rotation with the selector, and in which each of the plurality of chambers is disposed at the same distance from the second axis as the transfer conduit. This allows quick access to each of the chambers, and permits the item at the top of the stack to be quickly deposited in the catcher through the transfer conduit.
Preferably the chambers in the temporary storage unit are closed at one end by the selector when not in communication with the transfer conduit. Advantageously, this circumvents the need to provide some kind of clamp or catch to hold them in place. Each item will sit in its chamber until the chamber passes over the transfer conduit, at which point it may drop back into the array.
Preferably a low pressure source is used in fluid communication with the item transfer conduit to selectively suck items into the item transfer conduit from the array. The low pressure source is provided on the other side of the temporary storage unit to the selector such that the low pressure source selectively sucks items through the transfer conduit into the chamber in fluid communication with the transfer conduit. Advantageously, this means that mechanical engagement with each item or sample is not required. The fact that the system “sucks” the items from the volume also prevents the introduction of heat to the items by conduction, and instead surrounds them in cold air.
Because the low pressure source removes air from the volume, an aperture is provided to feed replacement air into the chamber. This air may be ambient (and then cooled by the cooling system of the tank) or pre-cooled using a refrigeration unit.
Preferably, the transfer conduit in the selector comprises an inlet seal, which seal bears against the array (or an array plate) of item storage formations. The seal preferably comprises an annular member rotatably (preferably spherically) mounted within the inlet. This allows the seal to better conform to, and form a substantially airtight seal with, the array plate. Preferably the seal forms a spherical joint with the selector, preferably via a part spherical surface engaging the inlet for this purpose.
Preferably an insulation layer is provided in the lid, and the temporary storage unit is positioned on the array side of the insulation layer. Preferably the first member comprises a first part of the insulation layer, and the temporary storage unit comprises a second part of the insulation layer, which first and second parts are adjacent to form a substantially contiguous insulation layer.
Advantageously, this keeps the temporarily stored items in the cold zone.
Turning to the array, it preferably comprises a plurality of elongate conduits parallel to the first and second axes, the selector being configured to selectively place each of the elongate conduits in communication with the transfer conduit or passage. The plurality of elongate conduits may be provided within pipes. Preferably the items are configured for axial sliding motion within the conduits or pipes. Samples can be “stacked” in the pipes. In order to maximise the available range of the system, preferably the array is annular about the first axis.
Preferably the array is annular about the first axis.
Preferably there is provided a plurality of items in the form of containers configured for axial sliding motion within the conduits.
Preferably the first member is rotatably mounted in a circular receiving formation of the tank, preferably in the tank lid or top plate. An annular running seal may be provided between the circular receiving formation and the first member.
The first member preferably comprises a layer of insulation material, which layer of insulation material defines a plurality of slits or recesses defined at least partially therethrough and facing the array. Because the layer of insulation is subject to a high temperature gradient (20 degrees ambient to minus 80 degrees inside the tank), thermally induced strains will try to develop, which could induce bending stresses in the first member. The slits allow the insulation to deform in small sections, reducing the bending stresses.
Preferably a separate access chamber is provided for the insertion and removal of items into and out of the array. This allows the picking mechanism to be sealed. Preferably the access chamber is in communication with a loading conduit which can be selectively placed in communication with the item receiving formation. Preferably the loading conduit forms part of the array. This allows the apparatus to load and unload items within its normal range of movement.
According to a second aspect of the invention there is provided a method of extracting an item from a storage apparatus comprising the steps of providing an array of items within a storage apparatus, providing a first member rotatable with respect to the array about a first axis, providing a selector rotatable with respect to the first member about a second axis, parallel to and offset from the first axis, the selector comprising an item transfer conduit, rotating the first member and the second member about the first and second axes respectively to align the item transfer conduit with an item to be extracted, using the selector to extract the item from the array.
As with the first aspect, the method uses an epicyclic selector to provide fast access to an annular array of item storage formations. The fact that the first member and the selector are rotated to position the item receiving formation makes them easier to seal against a tank wall.
Preferably the method further comprises the step of providing a low pressure source, using the low pressure source to suck the item into the item transfer conduit.
Further, the following steps are preferably part of the method providing a temporary storage unit, using the selector to extract multiple items from the array, temporarily storing the multiple items in the temporary storage unit, returning at least one of the multiple items to the array using the selector.
According to a third aspect of the invention, there is provided a suction apparatus for a storage apparatus comprising a conduit for the passage or storage of items, the conduit having an inlet, which suction apparatus comprises a seal member comprising a convex outer surface bearing against the conduit inlet to permit articulation of the seal member in use. Preferably, the convex outer surface is part spherical. The conduit may be provided with a part spherical concave formation to receive the seal member. Advantageously, this configuration allows the seal to better conform to the surface around orifices in an array in which items or samples may be stored, and thereby effect a better seal.